Disclosures About Fair Value of Financial Instruments - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Assets:
Cash and cash equivalents, Carrying Amount	$ 3,155,224	$ 455,806
Cash and cash equivalents, Estimated Fair Value	3,155,224	455,806
Debt securities, available for sale	2,797,940	2,961,015
Debt securities, held to maturity	1,258,560	840,259
Debt securities, held to maturity, fair value	1,212,248	793,813
Loans held for sale	78,108	328,312
Total loans and leases receivable, net of allowance for credit losses on loans and leases	13,693,143	15,335,435
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	13,298,144	14,890,823
FHLB, Federal Reserve Bank and other restricted stock, Carrying Amount	126,240	74,196
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	126,240	74,196
Derivative assets	26,003	44,435
Liabilities:
Deposits held	17,950,431	18,156,953
Deposits, Estimated Fair Value	17,923,322	18,127,338
FHLB advances, Carrying Amount	2,046,142	800,000
FHLB advances, Estimated Fair Value	2,029,664	781,113
Other borrowings, Carrying Amount	123,710	123,580
Other borrowings, Estimated Fair Value	100,666	108,081
Subordinated debt, Carrying Amount	182,091	181,952
Subordinated debt, Estimated Fair Value	148,371	168,441
Derivative liabilities	37,662	42,106
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents, Estimated Fair Value	3,155,224	455,806
Debt securities, available for sale	0	0
Debt securities, held to maturity, fair value	0	0
Loans held for sale	0	0
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	0	0
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	0	0
Derivative assets	0	0
Liabilities:
Deposits, Estimated Fair Value	13,093,728	13,907,087
FHLB advances, Estimated Fair Value	0	0
Other borrowings, Estimated Fair Value	0	0
Subordinated debt, Estimated Fair Value	0	0
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents, Estimated Fair Value	0	0
Debt securities, available for sale	2,746,115	2,887,749
Debt securities, held to maturity, fair value	497,814	437,680
Loans held for sale	1,234	322
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	1,006,268	1,323,312
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	126,240	74,196
Derivative assets	25,937	44,380
Liabilities:
Deposits, Estimated Fair Value	4,829,594	4,220,251
FHLB advances, Estimated Fair Value	2,029,664	781,113
Other borrowings, Estimated Fair Value	100,666	108,081
Subordinated debt, Estimated Fair Value	148,371	168,441
Derivative liabilities	37,662	42,106
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents, Estimated Fair Value	0	0
Debt securities, available for sale	51,825	73,266
Debt securities, held to maturity, fair value	714,434	356,133
Loans held for sale	76,874	327,990
Total loans and leases receivable, net of allowance for credit losses on loans and leases, Estimated Fair Value	12,291,876	13,567,511
FHLB, Federal Reserve Bank and other restricted stock, Estimated Fair Value	0	0
Derivative assets	66	55
Liabilities:
Deposits, Estimated Fair Value	0	0
FHLB advances, Estimated Fair Value	0	0
Other borrowings, Estimated Fair Value	0	0
Subordinated debt, Estimated Fair Value	0	0
Derivative liabilities	$ 0	$ 0